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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Test cases for compiler-based stack variable zeroing via
4 * -ftrivial-auto-var-init={zero,pattern}.
5 * For example, see:
6 * "Running tests with kunit_tool" at Documentation/dev-tools/kunit/start.rst
7 * ./tools/testing/kunit/kunit.py run stackinit [--raw_output] \
8 * --make_option LLVM=1 \
9 * --kconfig_add CONFIG_INIT_STACK_ALL_ZERO=y
10 *
11 */
12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14#include <kunit/test.h>
15#include <linux/init.h>
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/string.h>
19
20/* Exfiltration buffer. */
21#define MAX_VAR_SIZE 128
22static u8 check_buf[MAX_VAR_SIZE];
23
24/* Character array to trigger stack protector in all functions. */
25#define VAR_BUFFER 32
26
27/* Volatile mask to convince compiler to copy memory with 0xff. */
28static volatile u8 forced_mask = 0xff;
29
30/* Location and size tracking to validate fill and test are colocated. */
31static void *fill_start, *target_start;
32static size_t fill_size, target_size;
33
34static bool stackinit_range_contains(char *haystack_start, size_t haystack_size,
35 char *needle_start, size_t needle_size)
36{
37 if (needle_start >= haystack_start &&
38 needle_start + needle_size <= haystack_start + haystack_size)
39 return true;
40 return false;
41}
42
43/* Whether the test is expected to fail. */
44#define WANT_SUCCESS 0
45#define XFAIL 1
46
47#define DO_NOTHING_TYPE_SCALAR(var_type) var_type
48#define DO_NOTHING_TYPE_STRING(var_type) void
49#define DO_NOTHING_TYPE_STRUCT(var_type) void
50#define DO_NOTHING_TYPE_UNION(var_type) void
51
52#define DO_NOTHING_RETURN_SCALAR(ptr) *(ptr)
53#define DO_NOTHING_RETURN_STRING(ptr) /**/
54#define DO_NOTHING_RETURN_STRUCT(ptr) /**/
55#define DO_NOTHING_RETURN_UNION(ptr) /**/
56
57#define DO_NOTHING_CALL_SCALAR(var, name) \
58 (var) = do_nothing_ ## name(&(var))
59#define DO_NOTHING_CALL_STRING(var, name) \
60 do_nothing_ ## name(var)
61#define DO_NOTHING_CALL_STRUCT(var, name) \
62 do_nothing_ ## name(&(var))
63#define DO_NOTHING_CALL_UNION(var, name) \
64 do_nothing_ ## name(&(var))
65
66#define FETCH_ARG_SCALAR(var) &var
67#define FETCH_ARG_STRING(var) var
68#define FETCH_ARG_STRUCT(var) &var
69#define FETCH_ARG_UNION(var) &var
70
71/*
72 * On m68k, if the leaf function test variable is longer than 8 bytes,
73 * the start of the stack frame moves. 8 is sufficiently large to
74 * test m68k char arrays, but leave it at 16 for other architectures.
75 */
76#ifdef CONFIG_M68K
77#define FILL_SIZE_STRING 8
78#define FILL_SIZE_ARRAY 2
79#else
80#define FILL_SIZE_STRING 16
81#define FILL_SIZE_ARRAY 8
82#endif
83
84#define INIT_CLONE_SCALAR /**/
85#define INIT_CLONE_STRING [FILL_SIZE_STRING]
86#define INIT_CLONE_STRUCT /**/
87#define INIT_CLONE_UNION /**/
88
89#define ZERO_CLONE_SCALAR(zero) memset(&(zero), 0x00, sizeof(zero))
90#define ZERO_CLONE_STRING(zero) memset(&(zero), 0x00, sizeof(zero))
91/*
92 * For the struct, intentionally poison padding to see if it gets
93 * copied out in direct assignments.
94 * */
95#define ZERO_CLONE_STRUCT(zero) \
96 do { \
97 memset(&(zero), 0xFF, sizeof(zero)); \
98 zero.one = 0; \
99 zero.two = 0; \
100 zero.three = 0; \
101 zero.four = 0; \
102 } while (0)
103#define ZERO_CLONE_UNION(zero) ZERO_CLONE_STRUCT(zero)
104
105#define INIT_SCALAR_none(var_type) /**/
106#define INIT_SCALAR_zero(var_type) = 0
107
108#define INIT_STRING_none(var_type) [FILL_SIZE_STRING] /**/
109#define INIT_STRING_zero(var_type) [FILL_SIZE_STRING] = { }
110
111#define INIT_STRUCT_none(var_type) /**/
112#define INIT_STRUCT_zero(var_type) = { }
113#define INIT_STRUCT_old_zero(var_type) = { 0 }
114
115
116#define __static_partial { .two = 0, }
117#define __static_all { .one = 0, \
118 .two = 0, \
119 .three = 0, \
120 .four = 0, \
121 }
122#define __dynamic_partial { .two = arg->two, }
123#define __dynamic_all { .one = arg->one, \
124 .two = arg->two, \
125 .three = arg->three, \
126 .four = arg->four, \
127 }
128#define __runtime_partial var.two = 0
129#define __runtime_all var.one = 0; \
130 var.two = 0; \
131 var.three = 0; \
132 var.four = 0
133
134#define INIT_STRUCT_static_partial(var_type) \
135 = __static_partial
136#define INIT_STRUCT_static_all(var_type) \
137 = __static_all
138#define INIT_STRUCT_dynamic_partial(var_type) \
139 = __dynamic_partial
140#define INIT_STRUCT_dynamic_all(var_type) \
141 = __dynamic_all
142#define INIT_STRUCT_runtime_partial(var_type) \
143 ; __runtime_partial
144#define INIT_STRUCT_runtime_all(var_type) \
145 ; __runtime_all
146
147#define INIT_STRUCT_assigned_static_partial(var_type) \
148 ; var = (var_type)__static_partial
149#define INIT_STRUCT_assigned_static_all(var_type) \
150 ; var = (var_type)__static_all
151#define INIT_STRUCT_assigned_dynamic_partial(var_type) \
152 ; var = (var_type)__dynamic_partial
153#define INIT_STRUCT_assigned_dynamic_all(var_type) \
154 ; var = (var_type)__dynamic_all
155
156#define INIT_STRUCT_assigned_copy(var_type) \
157 ; var = *(arg)
158
159/* Union initialization is the same as structs. */
160#define INIT_UNION_none(var_type) INIT_STRUCT_none(var_type)
161#define INIT_UNION_zero(var_type) INIT_STRUCT_zero(var_type)
162#define INIT_UNION_old_zero(var_type) INIT_STRUCT_old_zero(var_type)
163
164#define INIT_UNION_static_partial(var_type) \
165 INIT_STRUCT_static_partial(var_type)
166#define INIT_UNION_static_all(var_type) \
167 INIT_STRUCT_static_all(var_type)
168#define INIT_UNION_dynamic_partial(var_type) \
169 INIT_STRUCT_dynamic_partial(var_type)
170#define INIT_UNION_dynamic_all(var_type) \
171 INIT_STRUCT_dynamic_all(var_type)
172#define INIT_UNION_runtime_partial(var_type) \
173 INIT_STRUCT_runtime_partial(var_type)
174#define INIT_UNION_runtime_all(var_type) \
175 INIT_STRUCT_runtime_all(var_type)
176#define INIT_UNION_assigned_static_partial(var_type) \
177 INIT_STRUCT_assigned_static_partial(var_type)
178#define INIT_UNION_assigned_static_all(var_type) \
179 INIT_STRUCT_assigned_static_all(var_type)
180#define INIT_UNION_assigned_dynamic_partial(var_type) \
181 INIT_STRUCT_assigned_dynamic_partial(var_type)
182#define INIT_UNION_assigned_dynamic_all(var_type) \
183 INIT_STRUCT_assigned_dynamic_all(var_type)
184#define INIT_UNION_assigned_copy(var_type) \
185 INIT_STRUCT_assigned_copy(var_type)
186
187/*
188 * The "did we actually fill the stack?" check value needs
189 * to be neither 0 nor any of the "pattern" bytes. The
190 * pattern bytes are compiler, architecture, and type based,
191 * so we have to pick a value that never appears for those
192 * combinations. Use 0x99 which is not 0xFF, 0xFE, nor 0xAA.
193 */
194#define FILL_BYTE 0x99
195
196/*
197 * @name: unique string name for the test
198 * @var_type: type to be tested for zeroing initialization
199 * @which: is this a SCALAR, STRING, or STRUCT type?
200 * @init_level: what kind of initialization is performed
201 * @xfail: is this test expected to fail?
202 */
203#define DEFINE_TEST_DRIVER(name, var_type, which, xfail) \
204/* Returns 0 on success, 1 on failure. */ \
205static noinline void test_ ## name (struct kunit *test) \
206{ \
207 var_type zero INIT_CLONE_ ## which; \
208 int ignored; \
209 u8 sum = 0, i; \
210 \
211 /* Notice when a new test is larger than expected. */ \
212 BUILD_BUG_ON(sizeof(zero) > MAX_VAR_SIZE); \
213 \
214 /* Fill clone type with zero for per-field init. */ \
215 ZERO_CLONE_ ## which(zero); \
216 /* Clear entire check buffer for 0xFF overlap test. */ \
217 memset(check_buf, 0x00, sizeof(check_buf)); \
218 /* Fill stack with FILL_BYTE. */ \
219 ignored = leaf_ ##name((unsigned long)&ignored, 1, \
220 FETCH_ARG_ ## which(zero)); \
221 /* Verify all bytes overwritten with FILL_BYTE. */ \
222 for (sum = 0, i = 0; i < target_size; i++) \
223 sum += (check_buf[i] != FILL_BYTE); \
224 /* Clear entire check buffer for later bit tests. */ \
225 memset(check_buf, 0x00, sizeof(check_buf)); \
226 /* Extract stack-defined variable contents. */ \
227 ignored = leaf_ ##name((unsigned long)&ignored, 0, \
228 FETCH_ARG_ ## which(zero)); \
229 /* \
230 * Delay the sum test to here to do as little as \
231 * possible between the two leaf function calls. \
232 */ \
233 KUNIT_ASSERT_EQ_MSG(test, sum, 0, \
234 "leaf fill was not 0x%02X!?\n", \
235 FILL_BYTE); \
236 \
237 /* Validate that compiler lined up fill and target. */ \
238 KUNIT_ASSERT_TRUE_MSG(test, \
239 stackinit_range_contains(fill_start, fill_size, \
240 target_start, target_size), \
241 "stackframe was not the same between calls!? " \
242 "(fill %zu wide, target offset by %d)\n", \
243 fill_size, \
244 (int)((ssize_t)(uintptr_t)fill_start - \
245 (ssize_t)(uintptr_t)target_start)); \
246 \
247 /* Validate check region has no FILL_BYTE bytes. */ \
248 for (sum = 0, i = 0; i < target_size; i++) \
249 sum += (check_buf[i] == FILL_BYTE); \
250 \
251 if (sum != 0 && xfail) \
252 kunit_skip(test, \
253 "XFAIL uninit bytes: %d\n", \
254 sum); \
255 KUNIT_ASSERT_EQ_MSG(test, sum, 0, \
256 "uninit bytes: %d\n", sum); \
257}
258#define DEFINE_TEST(name, var_type, which, init_level, xfail) \
259/* no-op to force compiler into ignoring "uninitialized" vars */\
260static noinline DO_NOTHING_TYPE_ ## which(var_type) \
261do_nothing_ ## name(var_type *ptr) \
262{ \
263 OPTIMIZER_HIDE_VAR(ptr); \
264 /* Will always be true, but compiler doesn't know. */ \
265 if ((unsigned long)ptr > 0x2) \
266 return DO_NOTHING_RETURN_ ## which(ptr); \
267 else \
268 return DO_NOTHING_RETURN_ ## which(ptr + 1); \
269} \
270static noinline int leaf_ ## name(unsigned long sp, bool fill, \
271 var_type *arg) \
272{ \
273 char buf[VAR_BUFFER]; \
274 var_type var \
275 INIT_ ## which ## _ ## init_level(var_type); \
276 \
277 target_start = &var; \
278 target_size = sizeof(var); \
279 /* \
280 * Keep this buffer around to make sure we've got a \
281 * stack frame of SOME kind... \
282 */ \
283 memset(buf, (char)(sp & 0xff), sizeof(buf)); \
284 /* Fill variable with FILL_BYTE. */ \
285 if (fill) { \
286 fill_start = &var; \
287 fill_size = sizeof(var); \
288 memset(fill_start, \
289 FILL_BYTE & forced_mask, \
290 fill_size); \
291 } \
292 \
293 /* Silence "never initialized" warnings. */ \
294 DO_NOTHING_CALL_ ## which(var, name); \
295 \
296 /* Exfiltrate "var". */ \
297 memcpy(check_buf, target_start, target_size); \
298 \
299 return (int)buf[0] | (int)buf[sizeof(buf) - 1]; \
300} \
301DEFINE_TEST_DRIVER(name, var_type, which, xfail)
302
303/* Structure with no padding. */
304struct test_packed {
305 unsigned long one;
306 unsigned long two;
307 unsigned long three;
308 unsigned long four;
309};
310
311/* Simple structure with padding likely to be covered by compiler. */
312struct test_small_hole {
313 size_t one;
314 char two;
315 /* 3 byte padding hole here. */
316 int three;
317 unsigned long four;
318};
319
320/* Trigger unhandled padding in a structure. */
321struct test_big_hole {
322 u8 one;
323 u8 two;
324 u8 three;
325 /* 61 byte padding hole here. */
326 u8 four __aligned(64);
327} __aligned(64);
328
329struct test_trailing_hole {
330 char *one;
331 char *two;
332 char *three;
333 char four;
334 /* "sizeof(unsigned long) - 1" byte padding hole here. */
335};
336
337/* Test if STRUCTLEAK is clearing structs with __user fields. */
338struct test_user {
339 u8 one;
340 unsigned long two;
341 char __user *three;
342 unsigned long four;
343};
344
345/* No padding: all members are the same size. */
346union test_same_sizes {
347 unsigned long one;
348 unsigned long two;
349 unsigned long three;
350 unsigned long four;
351};
352
353/* Mismatched sizes, with one and two being small */
354union test_small_start {
355 char one:1;
356 char two;
357 short three;
358 unsigned long four;
359 struct big_struct {
360 unsigned long array[FILL_SIZE_ARRAY];
361 } big;
362};
363
364/* Mismatched sizes, with three and four being small */
365union test_small_end {
366 short one;
367 unsigned long two;
368 char three:1;
369 char four;
370};
371
372#define ALWAYS_PASS WANT_SUCCESS
373#define ALWAYS_FAIL XFAIL
374
375#ifdef CONFIG_INIT_STACK_NONE
376# define USER_PASS XFAIL
377# define BYREF_PASS XFAIL
378# define STRONG_PASS XFAIL
379#else
380# define USER_PASS WANT_SUCCESS
381# define BYREF_PASS WANT_SUCCESS
382# define STRONG_PASS WANT_SUCCESS
383#endif
384
385#define DEFINE_SCALAR_TEST(name, init, xfail) \
386 DEFINE_TEST(name ## _ ## init, name, SCALAR, \
387 init, xfail)
388
389#define DEFINE_SCALAR_TESTS(init, xfail) \
390 DEFINE_SCALAR_TEST(u8, init, xfail); \
391 DEFINE_SCALAR_TEST(u16, init, xfail); \
392 DEFINE_SCALAR_TEST(u32, init, xfail); \
393 DEFINE_SCALAR_TEST(u64, init, xfail); \
394 DEFINE_TEST(char_array_ ## init, unsigned char, \
395 STRING, init, xfail)
396
397#define DEFINE_STRUCT_TEST(name, init, xfail) \
398 DEFINE_TEST(name ## _ ## init, \
399 struct test_ ## name, STRUCT, init, \
400 xfail)
401
402#define DEFINE_UNION_TEST(name, init, xfail) \
403 DEFINE_TEST(name ## _ ## init, \
404 union test_ ## name, STRUCT, init, \
405 xfail)
406
407#define DEFINE_STRUCT_TESTS(init, xfail) \
408 DEFINE_STRUCT_TEST(small_hole, init, xfail); \
409 DEFINE_STRUCT_TEST(big_hole, init, xfail); \
410 DEFINE_STRUCT_TEST(trailing_hole, init, xfail); \
411 DEFINE_STRUCT_TEST(packed, init, xfail)
412
413#define DEFINE_STRUCT_INITIALIZER_TESTS(base, xfail) \
414 DEFINE_STRUCT_TESTS(base ## _ ## partial, \
415 xfail); \
416 DEFINE_STRUCT_TESTS(base ## _ ## all, xfail)
417
418#define DEFINE_UNION_INITIALIZER_TESTS(base, xfail) \
419 DEFINE_UNION_TESTS(base ## _ ## partial, \
420 xfail); \
421 DEFINE_UNION_TESTS(base ## _ ## all, xfail)
422
423#define DEFINE_UNION_TESTS(init, xfail) \
424 DEFINE_UNION_TEST(same_sizes, init, xfail); \
425 DEFINE_UNION_TEST(small_start, init, xfail); \
426 DEFINE_UNION_TEST(small_end, init, xfail);
427
428/* These should be fully initialized all the time! */
429DEFINE_SCALAR_TESTS(zero, ALWAYS_PASS);
430DEFINE_STRUCT_TESTS(zero, ALWAYS_PASS);
431DEFINE_STRUCT_TESTS(old_zero, ALWAYS_PASS);
432DEFINE_UNION_TESTS(zero, ALWAYS_PASS);
433DEFINE_UNION_TESTS(old_zero, ALWAYS_PASS);
434/* Struct initializers: padding may be left uninitialized. */
435DEFINE_STRUCT_INITIALIZER_TESTS(static, STRONG_PASS);
436DEFINE_STRUCT_INITIALIZER_TESTS(dynamic, STRONG_PASS);
437DEFINE_STRUCT_INITIALIZER_TESTS(runtime, STRONG_PASS);
438DEFINE_STRUCT_INITIALIZER_TESTS(assigned_static, STRONG_PASS);
439DEFINE_STRUCT_INITIALIZER_TESTS(assigned_dynamic, STRONG_PASS);
440DEFINE_STRUCT_TESTS(assigned_copy, ALWAYS_FAIL);
441DEFINE_UNION_INITIALIZER_TESTS(static, STRONG_PASS);
442DEFINE_UNION_INITIALIZER_TESTS(dynamic, STRONG_PASS);
443DEFINE_UNION_INITIALIZER_TESTS(runtime, STRONG_PASS);
444DEFINE_UNION_INITIALIZER_TESTS(assigned_static, STRONG_PASS);
445DEFINE_UNION_INITIALIZER_TESTS(assigned_dynamic, STRONG_PASS);
446DEFINE_UNION_TESTS(assigned_copy, ALWAYS_FAIL);
447/* No initialization without compiler instrumentation. */
448DEFINE_SCALAR_TESTS(none, STRONG_PASS);
449DEFINE_STRUCT_TESTS(none, BYREF_PASS);
450/* Initialization of members with __user attribute. */
451DEFINE_TEST(user, struct test_user, STRUCT, none, USER_PASS);
452
453/*
454 * Check two uses through a variable declaration outside either path,
455 * which was noticed as a special case in porting earlier stack init
456 * compiler logic.
457 */
458static int noinline __leaf_switch_none(int path, bool fill)
459{
460 switch (path) {
461 /*
462 * This is intentionally unreachable. To silence the
463 * warning, build with -Wno-switch-unreachable
464 */
465 uint64_t var[10];
466
467 case 1:
468 target_start = &var;
469 target_size = sizeof(var);
470 if (fill) {
471 fill_start = &var;
472 fill_size = sizeof(var);
473
474 memset(fill_start, (forced_mask | 0x55) & FILL_BYTE, fill_size);
475 }
476 memcpy(check_buf, target_start, target_size);
477 break;
478 case 2:
479 target_start = &var;
480 target_size = sizeof(var);
481 if (fill) {
482 fill_start = &var;
483 fill_size = sizeof(var);
484
485 memset(fill_start, (forced_mask | 0xaa) & FILL_BYTE, fill_size);
486 }
487 memcpy(check_buf, target_start, target_size);
488 break;
489 default:
490 var[1] = 5;
491 return var[1] & forced_mask;
492 }
493 return 0;
494}
495
496static noinline int leaf_switch_1_none(unsigned long sp, bool fill,
497 uint64_t *arg)
498{
499 return __leaf_switch_none(1, fill);
500}
501
502static noinline int leaf_switch_2_none(unsigned long sp, bool fill,
503 uint64_t *arg)
504{
505 return __leaf_switch_none(2, fill);
506}
507
508/*
509 * These are expected to fail for most configurations because neither
510 * GCC nor Clang have a way to perform initialization of variables in
511 * non-code areas (i.e. in a switch statement before the first "case").
512 * https://llvm.org/pr44916
513 */
514DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, ALWAYS_FAIL);
515DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, ALWAYS_FAIL);
516
517#define KUNIT_test_scalars(init) \
518 KUNIT_CASE(test_u8_ ## init), \
519 KUNIT_CASE(test_u16_ ## init), \
520 KUNIT_CASE(test_u32_ ## init), \
521 KUNIT_CASE(test_u64_ ## init), \
522 KUNIT_CASE(test_char_array_ ## init)
523
524#define KUNIT_test_structs(init) \
525 KUNIT_CASE(test_small_hole_ ## init), \
526 KUNIT_CASE(test_big_hole_ ## init), \
527 KUNIT_CASE(test_trailing_hole_ ## init),\
528 KUNIT_CASE(test_packed_ ## init) \
529
530#define KUNIT_test_unions(init) \
531 KUNIT_CASE(test_same_sizes_ ## init), \
532 KUNIT_CASE(test_small_start_ ## init), \
533 KUNIT_CASE(test_small_end_ ## init) \
534
535static struct kunit_case stackinit_test_cases[] = {
536 /* These are explicitly initialized and should always pass. */
537 KUNIT_test_scalars(zero),
538 KUNIT_test_structs(zero),
539 KUNIT_test_structs(old_zero),
540 KUNIT_test_unions(zero),
541 KUNIT_test_unions(old_zero),
542 /* Padding here appears to be accidentally always initialized? */
543 KUNIT_test_structs(dynamic_partial),
544 KUNIT_test_structs(assigned_dynamic_partial),
545 KUNIT_test_unions(dynamic_partial),
546 KUNIT_test_unions(assigned_dynamic_partial),
547 /* Padding initialization depends on compiler behaviors. */
548 KUNIT_test_structs(static_partial),
549 KUNIT_test_structs(static_all),
550 KUNIT_test_structs(dynamic_all),
551 KUNIT_test_structs(runtime_partial),
552 KUNIT_test_structs(runtime_all),
553 KUNIT_test_structs(assigned_static_partial),
554 KUNIT_test_structs(assigned_static_all),
555 KUNIT_test_structs(assigned_dynamic_all),
556 KUNIT_test_unions(static_partial),
557 KUNIT_test_unions(static_all),
558 KUNIT_test_unions(dynamic_all),
559 KUNIT_test_unions(runtime_partial),
560 KUNIT_test_unions(runtime_all),
561 KUNIT_test_unions(assigned_static_partial),
562 KUNIT_test_unions(assigned_static_all),
563 KUNIT_test_unions(assigned_dynamic_all),
564 /* Everything fails this since it effectively performs a memcpy(). */
565 KUNIT_test_structs(assigned_copy),
566 KUNIT_test_unions(assigned_copy),
567 /* STRUCTLEAK_BYREF_ALL should cover everything from here down. */
568 KUNIT_test_scalars(none),
569 KUNIT_CASE(test_switch_1_none),
570 KUNIT_CASE(test_switch_2_none),
571 /* STRUCTLEAK_BYREF should cover from here down. */
572 KUNIT_test_structs(none),
573 /* STRUCTLEAK will only cover this. */
574 KUNIT_CASE(test_user),
575 {}
576};
577
578static struct kunit_suite stackinit_test_suite = {
579 .name = "stackinit",
580 .test_cases = stackinit_test_cases,
581};
582
583kunit_test_suites(&stackinit_test_suite);
584
585MODULE_DESCRIPTION("Test cases for compiler-based stack variable zeroing");
586MODULE_LICENSE("GPL");